HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 280, Issue 42, 35172-35183, October 21, 2005

This Article Full Text Full Text (PDF) All Versions of this Article: 280/42/35172    most recent M505559200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Folgueira, C. Articles by Requena, J. M. Search for Related Content PubMed PubMed Citation Articles by Folgueira, C. Articles by Requena, J. M. Social Bookmarking                      What's this?

The Translational Efficiencies of the Two Leishmania infantum HSP70 mRNAs, Differing in Their 3'-Untranslated Regions, Are Affected by Shifts in the Temperature of Growth through Different Mechanisms^*

From the Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, 28049 Madrid, Spain

Exposure of Leishmania promastigotes to the temperature of their mammalian hosts induces a typical heat-shock response. In Leishmania infantum, HSP70 is encoded by two types of genes that differ in their 3'-untranslated regions (3'-UTRs). Previously, we have shown that specific transcripts for each gene are present in promastigotes growing at normal temperature (26 °C), but only transcripts with 3'-UTR-type I (3'-UTRI) accumulate in a temperature-dependent manner. Here, we have investigated the translational efficiencies of both types of HSP70 transcripts at the different temperatures that the parasite encounters in the insect (26 °C, normal temperature) or in the mammalian host (heat-shock temperatures). Interestingly, 3'-UTRI-bearing transcripts (HSP70-I) were found associated with ribosomes in promastigotes at normal and heat-shock temperatures, whereas the HSP70-II transcripts appear to be preferentially translated at heat-shock temperatures but not at 26 °C. We have analyzed the function of these UTRs in the translational control by use of plasmid constructs in which the CAT reporter gene was flanked by UTRs of the HSP70 genes. Unexpectedly, it was found that CAT transcripts with 3'-UTRII bind to ribosomes at 26 °C, and, indeed, the CAT protein is synthesized. A valid conclusion of these experiments was that both types of 3'-UTRs are essential for translation of HSP70 mRNAs at heat shock temperatures, although the 3'-UTRII is more efficient during severe heat shock (39 °C). In addition, these results suggest that sequence region other than the 3'-UTR of HSP70-II gene is involved in the translational silent state of HSP70-II transcripts at 26 °C. Finally, a null mutant has been created by targeted disruption of both HSP70-II alleles. Remarkably, the HSP70 mutant synthesizes HSP70 at a lower rate than the wild-type parasites. Overall, our data suggest that the biological function of the HSP70-II gene is to top up HSP70 levels under conditions of stress.

Received for publication, May 20, 2005 , and in revised form, August 3, 2005.

^* This work was supported by the Spanish Ministerio de Ciencia y Tecnología (Grant BMC2002-04107-C02-01) and by an institutional grant from Fundación Ramón Areces. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed. Tel.: 34-914-978-454; Fax: 34-914-974-799; E-mail: jmrequena{at}cbm.uam.es.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				C. Dumas, C. Chow, M. Muller, and B. Papadopoulou A Novel Class of Developmentally Regulated Noncoding RNAs in Leishmania Eukaryot. Cell, December 1, 2006; 5(12): 2033 - 2046. [Abstract] [Full Text] [PDF]

				B. Rotureau, C. Ravel, M. Nacher, P. Couppie, I. Curtet, J.-P. Dedet, and B. Carme Molecular Epidemiology of Leishmania (Viannia) guyanensis in French Guiana J. Clin. Microbiol., February 1, 2006; 44(2): 468 - 473. [Abstract] [Full Text] [PDF]